Metallic fastener for envelopes



April 24, 1934. w 5w 1,955,896

METALLIC FASTENER FOR ENVELOPES Filed Oct. 26, 1931 lnv'eni on willar'd 6. 5:013 34 Bu A'Hzonney Patented 24, 19354- srss 1,955,896 METALLIC FAs'rENEn son ENVELOPES Willard Swift, Worcester, Mass, assignor to United States Envelope Company, Springfield, Mass, a corporation of Maine The invention relates to fasteners for attachment to envelopes. The fasteners are of the type in which a pair of bendable tongues are provided for insertion through a suitable opening in the flap of the envelope and are adapted to be spread apart after insertion in the opening, thereby to seal the flap in closed position. The metallic tongues on the fasteners of this type are usually formed integrally with a metallic base portion that provides attaching elements by which the fastener is secured to-the rear wall of the envelope. Such attaching elements have heretofore consisted of a plurality of single spurs located along the outside edge of the base portion or in other cases of a plurality of spurs radiating from one or more openings formed in the base plate.

Fasteners of the above and similar types have been produced and used in large quantities; it has been found that when the tongues are bent upwardly for insertion through the envelope flap the whole fastener is liable to become detached or torn from the envelope. In the case of fasteners secured to the envelope by a plurality of single spurs spaced around the edge of the base portion, 2 each spur holds but a small area of paper at a substantial distance from the center of the base portion and may be readily torn out or, by reason of the spaced relation of the spurs on the edges only, cause distortion of the base portion in response to the pull on the tongues. In this type of fasteners when the tongues are bent inwardly for insertion through the flap of the envelope, the pull exerted by the base portion away from the envelope wall results in a shearing action on the paper along the edges of the base portion with the possibility of the fastener being torn directly from the paper. In the case of fasteners provided with a plurality of spurs radiating from one or more openings, it will be seen that, by reason of the location of the attaching means extending from each opening within a small area on the paper, the strain imparted by the bending of the tongues is localized and the fastener is readily torn from the envelope. Accordingly, the present invention has for the principal object the provision of a fastener which embodies the advantages of the above types without including any of the disadvantages. According to the present invention, the fastener is provided with a plurality of separate attaching spurs which are so arranged in the base that each provides a comparatively large clamping area, and each clamping area at the same time is spaced a substantial distance from the center of the base portion of the fastener so that the points of attachment cover a large area, thereby to prevent excessive stress on the material of the envelope which would tear the fastener bodily from the envelope. At the same time, other attaching means are located substantially centrally of the base portion for securing the fastener to the material of the envelope substantially in line with the bendable tongues to hold the base portion against the envelope wall over its entire area. This cen- 69 trally located attachment overcomes the tendency to distortion of the base portion, and the fastener is secured to the envelope over substantially the entire area of the base portion.

The invention involves, in spite of the increased clamping action between the base portion and the material of the envelope, no increase in the area of the base portion so that the advantages of the present fastener are procured without the use of additional material in forming thefastoner. Certain of the attaching prongs in the present invention are bent outwardly away from the center of the base portion to distribute the strain resulting from bending of the tongues over a large area of the paper of the envelope, thereby to avoid the localized stresses adjacent the slit in the envelope through which the prong was inserted. Other advantages will more fully appear from the following description taken in connection with the accompanying drawing in which:-

Fig. 1 is a plan view of a portion of the envelope showing the novel fastener in position thereon with the sealing flap of the envelope in' open position.

Fig. 2 is a cross-sectional view on the line 2-2 of Fig. 1.

Fig. 3 is an enlarged plan View of a fastener constructed according to the invention;

Fig. 4 is a cross-sectional View on the line 44 of Fig. 3.

.Fig. 5 is a view of the inside of a portion of the envelope to which the novel fastener is secured showing the attaching prongs.

Like reference characters refer to like parts in the different figures.

Referring first to Figs. 1 and 2, an envelope 1 in connection with whichfasteners of this general type are usually employed comprises among other things a rear wall formed by flaps 2 and 3 which overlap each other, the outer flap 3 being outermost as here shown. Metallic fasteners are usually attached to the rear wall in the overlapping portion of the flaps to secure both flaps together, the attachment thus being in a reinforced or double portion of the envelope. The envelope also provides a front wall 4 having a closure flap 5 at the upper end thereof and said closure flap provides a reinforced opening 6 through which the tongues of the fastener are inserted in order to seal the envelope.

Referring now to Figs. 1 to 4 inclusive, the fastener of the invention is formed from sheet metal and comprises a pair of tongues 7 and 8 extending substantially from opposite sides of a central base or body portion 10 in alignment with each other. The body portion or base 10 is provided, on either side of the center line of the tongues, with a pair of integral oppositely extending lobeshaped extensions 11 and 12 parallel to the tongues 7 and 8 and spaced therefrom, as shown. Each extension is provided with an attaching prong 13 which is formed from the material of the base portion in any suitable manner as by the provision of a substantially U-shaped cut or slit 14 in the material of the base portion, parallel to the tongues '7 and 8 and opening outwardly, the line of attachment of the prong being perpendicular to the center line of the tongues and at the open end of the U-shaped slit. In the formation of the fastener, the attaching prongs in the lobes are bent outwardly from the plane of the base into a position substantially at right angles thereto, as best shown in Fig. 4, in readiness for insertion through the back wall of an envelope. It will be noted that the lines of attachment of the prongs to the base are all outside of and beyond the zones of flexure of the tongues '7 and 8 in a direction parallel to the center line of said tongues, said zones of fiexure being obviously at the bases of the tongues.

In addition to the attaching prongs 13, centrally located prongs 15 are provided substantially centrally of the base portion and adjacent the center line of the tongues. As best shown in Fig. 3, U-shaped slits 16 in the base portion determine the shape of the prong which is bent outwardly from the base portion at right angles thereto, Fig. 4. The lines of attachment of the prongs 15 to the base portion are spaced slightly above and below the center line of the tongues and are preferably located substantially in line with the edges of the tongues in parallel relation to said tongues. As will be seen from Fig. 3, the U-shaped slits by which the prongs 15 are formed extend outwardly from the line of attachment away from the center of the base so that when the prongs 15 are bent inwardly toward the center of the base portion they will engage a solid part of the base portion.

With the attaching prongs 13 and 15 of the fastener extending at right angles thereto, as shown in Figs. 3 and 4, the fastener is ready for attachment to an envelope. The attachment is efiected by forcing the fastener against the envelope to drive the prongs l3 and 14 through the double thickness of material of the rear wall of the envelope, after which the prongs are bent over against the rear wall to clamp the material 1 of said wall between said prongs and the base portion.

Referring to Fig. 5, the prongs 13, which, as above pointed out, have their line of attachment perpendicular to the center line of the tongues and spaced substantially therefrom, are bent outwardly away from the center of the base portion, to clamp the material of the envelope between said prongs and the adjacent area of the base portion. Since the prongs were formed from the material of the base portion inside of or toward the center from the line of attachment of said prong to the base, said prongs, when bent outwardly, engage solid material of the base portion and the entire surface of the prongs acts to clamp the material of the envelope securely, the spacing between the line of atachment of the prongs and the outer edge of the corresponding extension being at least as great as the length of the prong. The clamping action of the prongs on the envelope material is thus definitely outside of the zones of flexure of the tongues in a direction parallel to the center line of said tongues.

The prongs 15 are also bent inwardly after insertion of the prongs through the rear wall of the envelope to thereby clamp the material of the envelope between said prongs and the central portion of the base member. As above pointed out, these prongs are bent inwardly toward the center of the base portion to clamp the material of said wall between said prong and the solid material of the base portion whereby the entire surface of each of the prongs 15 functions in clamping the envelope material.

The prongs 13, as above pointed out, provide a clamping action outwardly from the slits in the paper through which the prongs are inserted so that, as the tongues 7 and 8 are bent together for insertion through the flap of the envelope, the resulting stress on the material of the envelope is spread over the entire clamping area of the four prongs 13, thereby avoiding any direct localizing strain on the material which would tend to rupture said material to allow the clasp to pull out of the envelope. At the same time the stress on each clamping area beneath the group 13 is minimized by the relatively wide spacing of the prongs from the center of the base and from each other. The prongs 15, engaging as they do the rear wall of the envelope substantially centrally of the base portion of the fastener and along the center line of the tongues, prevent any distortion or bending of the base away from the rear wall as the tongues are bent toward each other as might occur with the attaching means all spaced substantially from the center of the base portion. The prongs 15, in addition, secure the material of the envelope more positively to the base portion and provide additional attachment prongs more securely to hold the fastener in engagement with the envelope.

From a consideration of the drawing, it will be apparent that the prongs 13 support the clasp against strain particularly in the direction of the center line of the tongues, thereby to prevent tearing of the clasp from the envelope as the tongues are bent together for insertion through the flap of the envelope or when the tongues are bent outwardly for maintaining the flap in closed position. In addition to this securing action, the prongs 15 which extend through the rear wall of the, envelope at right angles to the prongs 13 support the fastener against strain perpendicularly to the center line of the tongues, resulting, for example, from movement of the tongues perpendicularly to the center line thereof as occurs.

in directing the tongues through the opening in the envelope flap. Moreover, the prongs 13 and 15 which, as above pointed out, support the fastener against strain in all directions, are spaced apart to cover a relatively large area, thereby preventing localized strains on the envelope wall.

From the foregoing, it will be apparent that the present fastener provides spaced securing means for the fastener at a substantial distance from Cal the center of the base portion as well as securing means substantially'centrally of the base portion. The invention further involves securing means which clamp the material of the envelope outwardly from the slits through which the means are inserted, thereby to avoid localized strain on the material. The securing means are formed from within the periphery of the base portion and bent in attachment against the solid material of the base to diminish the unit stress on the material of the envelope by increasing the area of the material clamped by the prongs, without an increase in the area of the fastener.

I claim,

1. A metallic fastener for envelopes comprising a base portion for attachment to an envelope wall, said base portion providing a pair of laterally and oppositely projecting tongues for insertion through an opening of the envelope flap, a plurality of prongs integral with the base portion and extending therefrom adjacent the outer periphery thereof, said prongs being spaced substantially from the center line of the tongues and from the center of the base, each of said prongs being formed from the base inwardly of the line of attachment of said prongs to the base, said line of attachment being substantially perpendicular to the tongues and beyond the zones of fiexure of said tongues in a direction parallel to the center line of said tongues, said prongs being bent outwardly against the base portion in attachment of said fastener to an envelope, the spacing of said line of attachment of the prongs from the periphery of the base being at least as great as the length of the prong.

2. A metallic fastener for envelopes comprising a base for attachment to an envelope wall, said base providing a pair of laterally and oppositely projecting tongues adapted for insertion through an opening in the envelope flap, a plurality of spaced prongs integral with said base and spaced substantially from the center thereof and from the center line of the tongues, said prongs being formed from the base inwardly of the line of attachment of said prongs, with said line of attachment spaced from the periphery of the base a distance at least as great as the length of the prong, and with the lines of attachment of said prongs positioned beyond the zones of flexure of the tongues in a direction parallel to the center line of said tongues, said prongs being bent v'outwardly against the base portion in attachment of said fastener to an envelope and other prongs 'integral with said base and adjacent the center thereof, said latter prongs being formed from the base outwardly of the line of attachment thereof, said first mentioned prongs being bent outwardly from the center of the base, and said last mentioned prongs being bent inwardly toward the center of the base in attachment of said fastener to an envelope, said prongs, when so bent, extending at least to the center line of the tongues.

WILLARD E. SWIFT. 

